Stain resist compositions based on hydrolyzed maleic anhydride polymers provide stain resistance towards acid dyes when applied from low pH aqueous solutions onto polyamide fibers. However, the fibers require a further treatment in an additional step with a fluorochemical dispersion to prevent soiling. This additional step can be costly since it requires application equipment and heating. To circumvent the additional costs, attempts have been made to modify maleic anhydride polymers by partial esterification with fluoroalcohols or fluorothiols as described by Pechhold and Murphy in U.S. Pat. No. 5,670,246. However, a drawback of this approach is the limited stability of the fluoroesters in low pH of less than about 2 in aqueous application baths.
Copolymers of non-hydrolyzable perfluoroalkyl monomers with maleic anhydride have been described by Pittman et al. in U.S. Pat. Nos. 3,844,827 and 4,029,867, and by Bildhauer et al. in Canadian Application 2,148,998. These fluorinated maleic acid polymers provide antisoil properties, but, they are unacceptable as anti-stain compositions.
There is thus a need for fluoropolymers which can be introduced into other polymer matrices to lower the surface energy and thus provide simultaneous soil and stain resistance in a single application step. The present invention provides such a polymer.